Systems and methods for indicating a quantity

Abstract

An indication device is provided which has an electrically conductive fluid driven by an MHD pump. The fluid has an indicator surface driven adjacent indices of an indicator so as to indicate a quantity. A position of the indicator surface is sensed and controlled to ensure accurate indication of the quantity. Optionally, the quantity indicated is time.

What is claimed is: 
     
       1. A wristwatch comprising a wrist band and at least one electrically conductive liquid driven by at least one pump for conductive liquids, wherein at least one segment of at least one liquid is used as an indicator in a capillary channel, said segment visible to an observer so as to indicate time to the observer, which segment the pump drives along adjacent indices of the indicator of time, wherein further the at least one liquid is enclosed in a rigid chamber of a closed loop that has at least one exposed, at least partially transparent surface allowing the observer to observe the position of the at least one segment of the liquid, the device further comprising a mechanism accommodating thermal expansion and/or contraction of the liquids, the mechanism being a gas-filled chamber portion of the rigid chamber disposed out of the field of view of the observer so as to be substantially invisible to the observer, wherein a meniscus of the segment of the at least one liquid is sensed and controlled to position the meniscus at a desired position to ensure accurate indication of time, and wherein capacitance or conductance is used to detect the position of the segment of the at least one liquid, so as to enable control thereof. 
     
     
       2. The device of  claim 1 , wherein the mechanism accommodating thermal expansion and/or contraction is a gas-filled indicator bubble in the at least one liquid. 
     
     
       3. The device of  claim 1 , wherein the mechanism accommodating thermal expansion or contraction is selected from a group of mechanisms consisting of a thin and flexible wafer enclosing the chamber in an airtight and watertight manner and disposed out of the field of view of the observer, a separate gas-filled chamber disposed out of the field of view of the observer, and a soft flexible material disposed in a portion of the chamber which is out of the field of view of the observer. 
     
     
       4. The device of  claim 1 , wherein the mechanism accommodating thermal expansion and/or contraction is a gas-filled chamber portion of the rigid chamber connected to the liquid-filled portion of the rigid chamber by a passageway portion of the rigid chamber. 
     
     
       5. The device of  claim 1 , wherein the pump is at least one MHD pump. 
     
     
       6. The device of  claim 5 , wherein the direction of motion of the liquid is changed by changing the polarity of the at least one MHD pump. 
     
     
       7. The device of  claim 1 , wherein at least one liquid is a colored liquid. 
     
     
       8. The device of  claim 1  in which the at least one liquid has the same refractive index as the rigid chamber. 
     
     
       9. The device of  claim 1 , wherein the at least one liquid has a suspended particulate visible to the observer. 
     
     
       10. The device of  claim 1 , wherein the liquid is contained in an elongated chamber. 
     
     
       11. The device of  claim 10 , wherein the elongated chamber is linear in form in portions thereof. 
     
     
       12. The device of  claim 10 , wherein the elongated chamber is nonlinear in form, preferably circular. 
     
     
       13. The device of  claim 1 , wherein the chamber is formed by two or more wafers, preferably connected to each other by bonding. 
     
     
       14. The device of  claim 1 , wherein the wafers are glass wafers. 
     
     
       15. The device of  claim 14 , wherein the chamber is formed by injection molding of the polymer. 
     
     
       16. The device of  claim 1 , wherein the chamber is formed by a polymer. 
     
     
       17. The device of  claim 1 , wherein the pump is at least two MHD pumps spaced apart along the elongated chamber so as to ensure that at any operational position of the liquid, the liquid can be pumped. 
     
     
       18. An indication device comprising at least one electrically conductive liquid driven by at least one magnetic pump for conductive liquids, wherein at least one segment of at least one liquid is used as an indicator, said segment visible to an observer so as to indicate a time quantity to the observer, which segment the pump drives along adjacent indices of the indicator of time, wherein further the at least one liquid is enclosed in a rigid chamber of a closed loop that has at least one exposed, at least partially transparent surface allowing the observer to observe the position of the at least one segment of the liquid, the device further comprising a mechanism accommodating thermal expansion and/or contraction of the liquids, the mechanism being a gas-filled chamber portion of the rigid chamber disposed out of the field of view of the observer so as to be substantially invisible to the observer. 
     
     
       19. An indication device comprising at least one electrically conductive liquid driven by at least one magnetic pump for conductive liquids, wherein at least one segment of at least one liquid is used as an indicator, said segment visible to an observer so as to indicate a time quantity to the observer, which segment the pump drives along adjacent indices of the indicator of time, wherein further the at least one liquid is enclosed in a rigid chamber of a closed loop that has at least one exposed, at least partially transparent surface allowing the observer to observe the position of the at least one segment of the liquid, the device further comprising a mechanism accommodating thermal expansion and/or contraction of the liquids, the mechanism being a gas-filled chamber portion of the rigid chamber disposed out of the field of view of the observer so as to be substantially invisible to the observer, wherein further, the chamber is formed by two or more wafers, preferably connected to each other by bonding. 
     
     
       20. An indication device comprising at least one electrically conductive liquid driven by at least one magnetic pump for conductive liquids, wherein at least one segment of at least one liquid is used as an indicator, said segment visible to an observer so as to indicate a time quantity to the observer, which segment the pump drives along adjacent indices of the indicator of time, wherein further the at least one liquid is enclosed in a rigid chamber of a closed loop that has at least one exposed, at least partially transparent surface allowing the observer to observe the position of the at least one segment of the liquid, the device further comprising a mechanism accommodating thermal expansion and/or contraction of the liquids, the mechanism being a gas-filled chamber portion of the rigid chamber disposed out of the field of view of the observer so as to be substantially invisible to the observer, wherein further the wafers are glass wafers.